d_identified_v | R Documentation |
d_identified_v
is the conditional probability density function (pdf) for
identified students. Unlike d_identified
, it is vectorized.
d_identified_v( x, relyt = 1, test.cutoff, mu = 0, valid = 1e-07, nom.cutoff = 1e-07, normalize = TRUE )
x |
The student's score on a standardized (z-score) metric. Interpreted
as a true score if a value is specified for |
relyt |
Confirmatory test reliability coefficient. Range (0, 1].
Must not be exactly 0. Defaults to 1; in this case, x is assumed
to be an observed score. If an alternative value is supplied for
|
test.cutoff |
Confirmatory test cutoff percentile. Range (0, 1). Must not be exactly 0 or 1. |
mu |
Population mean true score on a standardized (z-score) metric. Defaults to zero. |
valid |
Nomination validity coefficient. Controls the relatedness of the nomination scores and the confirmatory test scores. Range (0, 1). Must not be exactly 0 or 1, and must be less than the square root of the test reliability. |
nom.cutoff |
Nomination cutoff percentile. Range (0, 1). Must not be exactly 0 or 1. |
normalize |
Logical. Should the density be normalized to have a total area of one? Defaults to TRUE. |
See also p_identified
for the cumulative density, q_identified
for the quantile function, and r_identified
for random generation.
# un-normalized density for t=1.0 d_identified( relyt = .9, x = 1, test.cutoff = .9, nom.cutoff = .9, valid = .5, mu = 0, normalize = FALSE ) # normalized density for t=1.0 d_identified( relyt = .9, x = 1, test.cutoff = .9, nom.cutoff = .9, valid = .5, mu = 0, normalize = TRUE ) # compare the density of identified students for universal # screening vs. a poor-performing nomination stage # # area of each curve is proportion to the identification rate # under each system # create vector of true scores Tscores <- seq(0, 4, length.out = 200) # # plot the un-normed density for universal screening p.universal <- sapply(Tscores, d_identified, relyt = .9, test.cutoff = .9, normalize = FALSE ) plot( x = Tscores, y = p.universal, type = "l", xlab = "true score", col = "blue" ) # add the un-normed density for the bad system p.bad <- sapply(Tscores, d_identified, relyt = .9, test.cutoff = .9, nom.cutoff = .9, valid = .5, normalize = FALSE ) points(x = Tscores, y = p.bad, type = "l", col = "red")
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